In English

Quality assessment of LMD/w Ti-6Al-4V alloycomponents using conventional NDT techniques

Agnieszka Kisielewicz
Göteborg : Chalmers tekniska högskola, 2015. 87 s.
[Examensarbete på avancerad nivå]

In order to reduce costs of production and increase economic sustainability it is necessary to perform non-destructive tests at an early stage in the manufacturing process. Laser metal deposition (LMD) of titanium alloys using wire feed technology is a fairly young technology and is still in a developing stage. Thus the necessity of introducing non-destructive examination adapted to LMD/wire parts is even higher. The main purpose of the project was to evaluate usability of ultrasonic immersion testing for detecting lack of fusion defects in specific LMD test samples. Additionally, eddy current technique was examined as probable complementary inspection. Initially, theoretical study was performed on applying ultrasonic tests to LMD parts as well as on the characteristics of lack of fusion and its detectability. The experimental part of ultrasonic tests consisted of evaluation of available probes for the application, creating and optimizing amplification curves according to the reference as well as performing planar scans on available samples. Different incidence surfaces and their conditions were evaluated in terms of usability for inspection. As the result, several inspection limitations were identified. Subsequently, complimentary theoretical study was performed focusing on eddy current inspection. Eddy current experiments were performed on reference plate, using both plane surface as well as surface containing notches. Additionally, scans were performed on LMD/w samples with two different surface conditions. Comparison of the results was provided. Applying ultrasonic immersion testing for LMD/w test pieces showed satisfying results in terms of usability of the method. The results of the ultrasonic testing revealed a number of limitations when it came to inspection capabilities. To start with, raw surface conditions reduced the reliability of the inspection. Certain volumes close to the incidence surface as well as close to the edges of component were restricted from inspection. Using optimized settings it was possible to detect flaws producing signals comparable to the target (i.e. 0.4 mm flat bottom hole). Eddy current inspection showed capabilities of being used as a complementary method for inspection of limited volumes of close to the edge area. Yet, the conclusion was based mainly on reference defects. Additionally, depending on the size of reference defects, the detectability of flaws varied regarding to the depth. The milled surface condition of LMD parts provides similar inspection conditions to the ones of reference plate.



Publikationen registrerades 2015-09-09.

CPL ID: 222131

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